Several electric bulbs designed to he used on a 220 V electric supply line, are rated 10 W. How many lamps can be connected in parallel with each other across the two wires of 220V line of the maximum allowable current is 5A ?

Explanation

Resistance of each bulb = R[say]
`R=V^(2)/P=(220xx220)/10=4840Omega`
Let n such bulbs be connected in parallel. Then `1/R_(p)=1/4840+1/4840+.....n" times"=n/4840`
`R_(p)=4840/nOmega`
`R_(p)=V/IrArrI=V/R_(p)`
`5ge(220n)/4840`
`nle110`
Number of electric bulbs = 110.